As shown in FIG. 1, a vision correcting device of the prior art is intended for use in correcting the farsightedness or the nearsightedness and is composed of a farsightedness or the nearsightedness and is composed of a shield 1, a gas tube 2, and a pressure apparatus 3. The pressure apparatus 3 is a spherical air sac of a plastic material. When the pressure apparatus 3 is squeezed with hand, an increase in the air pressure inside the shield 1 is brought about so as to cause a reduction in the curvature of the eye lens of a person under treatment for myopia. On the other hand, when the pressure apparatus 3 is relieved of the external force exerting thereon, a reduction in the air pressure inside the shield 1 is brought about so as to cause an increase in the curvature of the eye lens of a person under treatment for hyperopia. Such a manually-operated pressure apparatus 3 as described above is limited in design in that it does not provide the shield 1 with the desired air pressure with precision, and that it is difficult for a person, especially a youngster, to operate correctly and precisely.